1. Field of the Invention
This invention relates to an intelligent controller having a control path and a data path to the controller separately accessed through addressable virtual space. The invention also relates to a computer peripheral system architecture and a control system protocol capable of communicating commands, messages, control information and data between a peripheral system and one or more host computers in a manner independent of the type of peripheral devices and the type of host computers.
2. Description of the Related Art
Computing systems having a peripheral system.connected to the host through a controller are of course well known. Particularly, computing systems having a large mass storage system connected as a part of a virtual file system are known. Such a system has been implemented with a computing system having a peripheral system adapter in a virtual file system connected through a SCSI (Small Computing System Interface) bus to a peripheral file system containing the mass storage system. The peripheral system adapter provides the interface between the virtual file system and the host and the peripheral file system. The host system is a UNIX system. As is well known, the virtual file system protocol, along with entities in the virtual file system being identified as xe2x80x9cvnodes,xe2x80x9d allows the virtual file system to incorporate multiple types of file systems into a virtual file system that appears to the host as a single system.
The system calls at the host are converted to vnode file commands at the virtual file system. The vnode file commands, along with embedded data in each command, are passed to the peripheral file system. The peripheral file system converts the vnode file commands to driver commands, and executes the commands to handle the data passed with the vnode file commands.
The problem with communicating with the peripheral file system through vnode file commands with embedded data is that the communication is quite limited compared to the capability of the peripheral file system. File systems are designed to optimize data transfer operations as in DMA (Direct Memory Access) operations. By communicating vnode commands with embedded data between the peripheral file system and the host, the embedded data is neither block-aligned nor page-aligned. Aligning this data to appropriate boundaries, so that it is useable, requires an extra copy step. Also, by communicating the data embedded in the vnode commands, the handling of the data requires all the overhead associated with processing commands. This is in stark contrast to DMA operations where data with proper page blocks is transferred directly between memory and disk drive.
What is needed is a mass storage system controller and a communication protocol between the virtual file system at the host and the storage system controller so that commands from the host to the controller are standard commands, and data can be presented back to the host in a proper form to be passed in a DMA operation.
Partial Summary of Features
In accordance with this invention, the above problems have been solved by providing access to data in a peripheral system controlled by an intelligent controller, and this access is provided as if the intelligent controller were an addressable virtual storage space. This is accomplished first by communicating controller commands for the intelligent controller through read/write commands addressed to a Command Region of a virtual storage device.
The controller commands set up a Mapped Data Region in the virtual storage device for use in data transfer operations to and from the peripheral system. With the Mapped Data Regions set up, blocks of data are transferred between the host and the intelligent controller through read/write commands addressed to the Mapped Data Region of the virtual storage device.
In an additional feature of the invention, file operations are communicated between host and controller through a device driver at the host and a device emulator at the intelligent controller. If the address in the device write/read command is pointing to the Command Region of the virtual storage device, a Command Region process interprets and implements the controller operation required by the controller command embedded in the device write/read command. One of these controller commands causes the Command Region process to map a requested file or file portion to a Mapped Data Region in the virtual storage device. If the address detected in the device write/read command is in a Mapped Data Region, a Mapped Data Region process is called. The Mapped Data Region process reads or writes a requested file or file portion mapped to the Mapped Data Region addressed by the read/write command. This mapped file read or write is accomplished as a transfer of data separate from the transfer of commands.
In an additional feature of the invention, the data transfer between host system and intelligent controller is accomplished by performing a direct memory access transfer of data.
Utility and Advantages
This invention provides a new architecture to allow multiple computers with different operating systems to share data and storage at storage speeds. Many of the limitations of today""s storage devices can be eliminated with this new architecture. Further, this architecture is able to integrate new ideas and functionality without disruption of the existing behavior or causing significant impact to the operating system itself
When multiple host computers attempt to access the storage system, all unused storage space is available to any host connected. The storage space is not prepartitioned among hosts. Hosts are allocated storage as needed. If one host needs the storage, it can use any or all of the available space. If a host deletes a file, that space is available to any other host. This dynamic storage sharing operates automatically and transparently. Also, it does not matter what type of host is connected to the storage system controller so multiple types of hosts may be connected to the same intelligent controller.
Data can be shared by multiple hosts, and this data sharing is at the storage level. Two hosts connected to the same storage can copy, move, or access each other""s data at the storage level. Each host has access to any file written by any host. When one user writes a file, that file is available to any other user on any other host, given the correct permissions. All this is done without burdening any other computer or any network connecting the host computers.
This invention provides an intelligent controller capable of dynamic storage sharing and true data sharing to block level devices. The advantages of such a combined system are enormous. Any server, no matter what operating system it is running, can access and modify files written by any other server, no matter its operating system, directly at storage interface speeds. No copy need be involved. Any server can use any available storage. No longer are administrators required to unload data from a RAID device, reconfigure the partitions to add more storage to a full partition, and then reload the data, all while the data is inaccessible by users.
Storage Area Networks (SAN) will benefit most from the architecture of this invention. Dissimilar servers can be connected to the SAN and share data and storage. Storage can be added to the network independent of the hosts. Any existing addressable storage can remain on the same interconnect, albeit with the same limitations.
The invention is storage technology independent. Storage technology vendors can develop and support storage devices with vastly different characteristics with the same host integration. RAID, optical DVD towers, jukeboxes, etc., can all have the same interface to the host computer. This means storage vendors can release technology independent of operating system schedules to get solutions to their customers sooner.
The invention allows capacity to be added seamlessly without the need to bring the system down for a long reconfiguration process. Existing data does not need to be offloaded then reloaded when the capacity is added. . After new space is added, it is available to any host. Any file can become larger and any directory can hold more files.
Other features, utilities and advantages of the invention will be understood by those of ordinary skill in the art after referring to the complete written description of the preferred embodiments of the invention in conjunction with the following drawings.